An extension of the ASP.NET MVC WebGrid HTML helper to add a total row

ExampleUsage

In the ViewModel or Controller, create a new TotalWebGrid and return it to the view, just like with the normal WebGrid.

public TotalWebGrid Grid
{
     get
     {
                return new TotalWebGrid(
                            source: stagingBillLines,
                            rowsPerPage: 10,
                            ajaxUpdateContainerId: "BillLines");
     }
}


In the view add a TotalWebGridColumn. Set the Total property to true. This will sum this column and add the sum to the total row. Additionally you can assign a format and a CSS style to the total cell.
@{
    var columns = new List<TotalWebGridColumn>();
    columns.Add(new TotalWebGridColumn
    {
        ColumnName = "Charges",
        Header = "Charges",
        Total = true,
        TotalFormat = "{0:C2}",
        Style = "total"
    });
}
@Model.Grid.GetHtml(columns: columns)

TotalWebGrid.cs

    public class TotalWebGrid : WebGrid
    {
        //Extends the built in MVC WebGrid to add a total row

        private bool _canPage;
        public TotalWebGrid(IEnumerable<dynamic> source = null,
                              IEnumerable<string> columnNames = null,
                              string defaultSort = null,
                              int rowsPerPage = 10,
                              bool canPage = true,
                              bool canSort = true,
                              string ajaxUpdateContainerId = null,
                              string ajaxUpdateCallback = null,
                              string fieldNamePrefix = null,
                              string pageFieldName = null,
                              string selectionFieldName = null,
                              string sortFieldName = null,
                              string sortDirectionFieldName = null)
            : base(
              source,
              columnNames,
              defaultSort,
              rowsPerPage,
              canPage = true,
              canSort,
              ajaxUpdateContainerId,
              ajaxUpdateCallback,
              fieldNamePrefix,
              pageFieldName,
              selectionFieldName,
              sortFieldName,
              sortDirectionFieldName)
        {
            _canPage = canPage;
        }

        /// <param name="displayTotal">Whether the total row should be displayed</param>
        /// <param name="totalRowStyle">Classes for styling the total row</param>
        public IHtmlString GetHtml(
            string tableStyle = null,
            string headerStyle = null,
            string footerStyle = null,
            string rowStyle = null,
            string alternatingRowStyle = null,
            string selectedRowStyle = null,
            string caption = null,
            bool displayHeader = true,
            bool fillEmptyRows = false,
            string emptyRowCellValue = null,
            IEnumerable<TotalWebGridColumn> columns = null,
            IEnumerable<string> exclusions = null,
            WebGridPagerModes mode = WebGridPagerModes.NextPrevious | WebGridPagerModes.Numeric,
            string firstText = null,
            string previousText = null,
            string nextText = null,
            string lastText = null,
            int numericLinksCount = 5,
            object htmlAttributes = null,
            bool displayTotal = false,
            string totalRowStyle = null)
        {
            Func<dynamic, object> footer = null;
            if (_canPage && (PageCount > 1))
            {
                footer = item => Pager(mode, firstText, previousText, nextText, lastText, numericLinksCount);
            }

            return Table(tableStyle, headerStyle, footerStyle, rowStyle, alternatingRowStyle, selectedRowStyle, caption, displayHeader,
                fillEmptyRows, emptyRowCellValue, columns, exclusions, displayTotal, totalRowStyle, footer: footer,
                htmlAttributes: htmlAttributes);
        }

        public IHtmlString Table(
            string tableStyle = null,
            string headerStyle = null,
            string footerStyle = null,
            string rowStyle = null,
            string alternatingRowStyle = null,
            string selectedRowStyle = null,
            string caption = null,
            bool displayHeader = true,
            bool fillEmptyRows = false,
            string emptyRowCellValue = null,
            IEnumerable<TotalWebGridColumn> columns = null,
            IEnumerable<string> exclusions = null,
            bool displayTotal = false,
            string totalRowStyle = null,
            Func<dynamic, object> footer = null,
            object htmlAttributes = null)
        {
            IHtmlString html;
            if (displayTotal)
            {
                string totalRow = BuildTotalRow(this.Rows, totalRowStyle, columns);
                string baseHtml = base.Table(tableStyle, headerStyle, footerStyle, rowStyle, alternatingRowStyle, selectedRowStyle, caption, displayHeader, fillEmptyRows, emptyRowCellValue, columns, exclusions, footer, htmlAttributes).ToString();
                string htmlWithTotal = baseHtml.Replace("</tbody></table>", totalRow);

                html = new HtmlString(htmlWithTotal);
            }
            else
            {
                html = base.Table(tableStyle, headerStyle, footerStyle, rowStyle, alternatingRowStyle, selectedRowStyle, caption, displayHeader, fillEmptyRows, emptyRowCellValue, columns, exclusions, footer, htmlAttributes);
            }

            return html;
        }

        private string BuildTotalRow(IList<WebGridRow> rows, string totalRowStyle, IEnumerable<TotalWebGridColumn> columns)
        {
            var rowTag = string.Format("<tr class=\"{0}\">", totalRowStyle);

            StringBuilder rowStringBuilder = new StringBuilder(rowTag);
            foreach (var column in columns)
            {
                //Check if this column should be totaled
                if (column.Total)
                {
                    //Sum the column by looping through each row, getting the value, and adding it to the total
                    decimal columnTotal = 0;
                    foreach (var row in rows)
                    {
                        decimal cellValue = 0;
                        try
                        {
                            //Get the value in the column for this particular row
                            Type rowType = row.Value.GetType();
                            PropertyInfo rowProperty = rowType.GetProperty(column.ColumnName);
                            var propertyValue = rowProperty.GetValue(row.Value, null);
                            decimal.TryParse(propertyValue.ToString(), out cellValue);
                        }
                        //If exception is RuntimBinderException most likely the value is null and can't be summed anyway, so move on
                        catch (RuntimeBinderException) { }

                        columnTotal += cellValue;
                    }

                    //Format the total based on the user specified format
                    string totalFormat = column.TotalFormat == null ? "{0:0.00}" : column.TotalFormat;
                    var formattedTotal = string.Format(totalFormat, columnTotal);

                    //Create a new table cell tag containing the total and append it to the output string
                    var td = new TagBuilder("td");
                    td.MergeAttribute("class", column.TotalStyle);
                    td.InnerHtml = formattedTotal;

                    rowStringBuilder.Append(td.ToString());
                }
                else
                {
                    //If the column shouldn't be totaled just append an empty table cell
                    var td = new TagBuilder("td");
                    rowStringBuilder.Append(td.ToString());
                }
            }
            rowStringBuilder.Append("</tr></tbody></table>");

            return rowStringBuilder.ToString();
        }
    }

TotalWebGridColumn.cs

    public class TotalWebGridColumn : WebGridColumn
    {
        public bool Total { get; set; }
        public string TotalFormat { get; set; }
        public string TotalStyle { get; set; }
    }